New research out of Barcelona provides evidence that COVID-19 may be a seasonal illness not unlike the flu, touching on one of the questions that have been around since the start of the pandemic. Among other things, the scientists found that COVID-19 transmission rates were higher in regions that had low humidity and temperatures, as well as consistent patterns from the first through third waves of the pandemic.
The new study comes from the Barcelona Institute for Global Health (ISGlobal); it was published in the peer-reviewed journal Nature Computational Science. The team looked at the initial phase of COVID-19 spread across 162 countries in relation to the local humidity and temperature levels. The data was pulled before public health policies were rolled out and people began to change their behaviors.
In addition, the study looked at the link between climate from the local to a worldwide level and how the virus evolved over time. The researchers found that when temperature and humidity levels were lower, the rate of COVID-19 transmission was higher. The team explains they found “consistent patterns” at different geographic scales (cities, countries, etc.) during the first, second, and their pandemic waves.
For example, the analysis found that the first COVID-19 waves slowed down as humidity and temperature levels increased, while the second waves started when the climate began to cool down again. The only exception was the summertime, which broke the pattern across all continents potentially due to things like increased tourism and group gatherings.
Beyond that, the researchers used an epidemiological model to demonstrate that factoring in the climate with transmission rate improves the prediction of when COVID-19 waves will increase and decrease. In addition to improving predictions, the researchers note that their study indicates a greater need for what they call ‘air hygiene,’ referring to indoor ventilation to help reduce aerosol spread.